I need some help with a server

so ive been trying to set up a server but when im in the steam cmd and i do app_update it says “no subscription”.
what should i do?

Do you have a beta key for the server ?
If you don’t, you can’t set up a server at this moment. The servers are for selected hosters only.

ow okay, but how do i get a beta key?

try to email garry. But if you’re not a existing hoster who sells gameservers, you’ll not get a key.